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Cartogrammar Poster

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Cartogrammar Poster

  1. 1. AIM & OBJECTIVESThe aim of the Cartogrammar project was to address two principal barriers to uptake and use ofcartograms by a wider social science audience:(i) lack of an easy to use production facility and(ii) inherent computational resource barriers.These aims have been addressed by the creation of a robust, production level service throughthe implementation of an API allowing the integration of on demand cartogram generation facilitywhich moves any necessary computational expense to the server end thus removing any clientside bottlenecks.Recognising that the API itself is of limited utility to casual users, we have exploited thedevelopment of the API and used it to drive the core functionality of the accompanying website,gallery and widget. This site acts as an interface for non-specialists, providing the functionality togenerate and download bespoke cartograms and search and download cartograms from the usercontributed gallery.The terms and conditions of use are based on an OpenDatabase Commons licensing frameworkensuring that through the gallery other social scientists can reap the benefits of the data createdby others.End users can also generate html for embedding in their own website enabling them to generatecartograms.NON TECH SUMMARYA cartogram is effectively a transformed map visualisation of data. The transformation isusually based around some thematic mapping variable e.g. population or share of electoral vote.The geometry or spatial configuration of the map is distorted in order to convey the informationof this alternate variable. The ultimate rationale behind re-projecting map data in this fashion is toovercome the inherent bias traditional maps convey in as much that they tend to over-exaggeratethe importance of larger areas as opposed to smaller ones i.e. they give visual dominance to thegeographic area rather than the variable of interest under study.The Cartogrammar project offers a production strength generic service and associated toolsetwhich breaks the two main barriers associated with production of cartograms i.e. complexity andcomputational expense. This has been achieved through the development of:• a WebsiteThe website is available at and provides an easy to use cartogramgeneration interface for non-specialists to use. It also provides a searchable gallery of user con-tributed cartograms for viewing and downloading.• an APIThe API is accessed through the use of the HTTP protocol and is employed as a RESTful webservice. The API documentation is available for download from the Cartogrammar website.• an embeddable widget.Users can also generate an html <iframe> code snippet allowing them to embed the cartogramproduction capability on their own website.ABOUT THE SITEThe Cartogrammar site is designed to assist in the production of Cartograms.The website offers:• A web based interface to capture the Cartogram generation parameters• Cartogram production on EDINA compute infrastructure• Cartogram delivery through the website Gallery• Access to an API for direct interaction• The ability to generate the HTML required to embed the production functionality within another websiteThe Cartogrammar API is based on ScapeToad1which is a cross-platform, open-source applicationwritten in Java, designed as an independent application using the ESRI Shapefile format for input andoutput. It uses the Gastner/Newman [2004] diffusion-based algorithm to adapt map surfaces to user-defined variables without altering their topological relations2.The project was supported by the ESRC and developed by EDINA at University of Edinburgh.1 IS A CARTOGRAM?A Cartogram may be defined variously as :• A special type of map which attempts to convey a general sense of geography in addition to one ormore other important statistical elements.• A small diagram, on the face of a map, showing quantitative information.• An abstracted and simplified map the base of which is not true to scale.CARTOGRAM EXAMPLES